Background: AcQMap charge density mapping reveals regions with localised irregular activation (LIA) during AF. The conduction properties of these regions in sinus rhythm is poorly understood.
Objective: To compare conduction velocity (CV) during pacing between regions identified as LIA versus more uniform, passive activation during AF.
Methods: Patients undergoing AcQMap guided ablation were studied. 30second recordings of AF propagation and during pacing at 800ms cycle length from either the coronary sinus or left atrial appendage were obtained. External cardioversion to restore sinus rhythm or burst pacing to induce AF were used as necessary. LIA regions were identified using the in-built AcQTrack tool. Additional regions equidistant from the pacing site that displayed more uniform ‘passive’ activation were chosen for comparison. Following demarcation of these zones, pacing maps were created and exported for analysis. Local CV was estimated using a method of polynomial surface fitting and the median value was compared between regions. Differences in CV were compared using a paired t-test.
Results: A total of 12 patients were included (age 62, male = 7, BMI 31.6, ejection fraction 44%, left atrial diameter 44mm). In the 12 patients, 14 regions of LIA and paired regions with uniform propagation were identified. Median CV in LIA regions was 0.67±0.28m/s compared to 1.34±0.90m/s in regions with uniform CV with a difference of 0.67, 95% confidence interval 0.18 - 1.16, p=0.012.
Conclusion: Regions with significant LIA during AF demonstrate relatively slow CV during pacing compared to adjacent zones with uniform propagation suggestive of a possible role of these zones in AF maintenance.